Inform user to target correct backup folder after upgrading to 6.2.0

[federicoiosue]

When coming from version 6.1.0, where the default backups' folder was the sdcard's main folder, the customer has to decide which folder give access the ON 6.2.0 app to.

• Targeting the previously created /sdcard/Omni Notes folder would create a new Omni Notes folder in it but will miss the old backups (because it'll search for an inner tree).
• Targeting the old /sdcardfolder is not an option due to secure storage management restrictions

Find a way out.

1. Inform the user to manually move the folder within the changelog.
2. ?

[federicoiosue]

Forcing changelog on app's start when upgrading would help

PackageInfo packageInfo = activity.getPackageManager()
    .getPackageInfo(activity.getPackageName(), 0);
int versionCode = packageInfo.versionCode;